Iran's Foreign Ministry spokesman said on Saturday that Syrian rebels are responsible for the safety of 48 Iranians kidnapped in August, the Iranian Labor News Agency (ILNA) reported.
The Syrian rebels said in a video posted on YouTube that they would start to execute the Iranians, whom it says are members of the Iranian Revolutionary Guard Corps (IRGC) if Iran and Syria do not stop striking Syrian citizens.
The video shows a rebel officer dressed in army fatigues standing in front of a group of hostages. The officer said that the execution threats came after the failure of negotiations with the Syrian authorities to exchange the Iranians for Syrian rebel prisoners.
According to ILNA, Ramin Mehmanparast said Iran "condemned the continuing lack of freedom of Iranian pilgrims in Syria."
"The responsibility for their lives lies with their kidnappers and their supporters," the foreign ministry spokesman added.
Mehmanparast said that the "use of defenseless pilgrims as human shields goes against the principles of human rights."
Iranian officials have claimed that the 48 hostages are Shiite pilgrims and an Afghani interpreter who visited Syria for religious reasons. According to Iran, they were kidnapped just outside Damascus as they visited the shrine of Hazrat Zainab, the daughter of Imam Ali.
However, their Syrian rebel captors say the 48 men are IRGC members who came to Syria to help president Bashar Assad's forces quash the rebellion against his regime.
Though Iran denies that the hostages were in Syria for military reasons, Iran's Foreign Minister Ali Akbar Salehi has previously said that one of those kidnapped was a retired IRGC member.
In May, Iran admitted for the first time that members of the IRGC's extraterritorial unit, the Qods Force, are in Syria. Qods Force deputy commander Esmail Gha'ani said that the IRGC was aiding Syria, in a report that was quickly removed from Iranian news websites.
Last week, Hojjat al-Eslam Ali Shirazi, Supreme Leader Ali Khamenei's representative to the Qods Force, said that Iran was providing "consultation and advice" to Assad.
"We don't see any reason for an expansive military presence in Syria," Shirazi said, adding that the Syrian Army could put down the rebellion themselves.
In a press conference last month, IRGC commander Brigadier General Mohammad Ali Jafari also admitted that the Qods Force was aiding Assad in Syria but denied that it was acting in a military capacity.
"Ever since the Qods Force was formed, its aim has been to protect innocent peoples, especially Muslims. A number of Qods Force [members] are in Syria but not as a military presence in that country," Jafari told reporters in September, according to the Iranian Students News Agency (ISNA).